Thermostatic damper control



i6, E4; J, G, DUNVILLE 2,437,878

' THERMOSTATIC DAMPER CONTROL` Filed June 7, 1945 Patented Mar. 16, 1948 @ambrosiano mman coNTRoL 3,011,116- Dunville, Chicago, V111i., asssne' `t0 Sears, Roebuck' and 'Coi;`j`Ch icago, 111., V'a corporation Application Junej, 1943,.,sue1yis1 N o. 489,394.

changes of temperature of v,the air enteringvthe A4L dans'. (c1. 23e-e3) supply duct. Such control ispartiedlarlyadapted for use on small stoves orheailers 'which are used to neat the air inthe ltQQmin whichthey are located, Asince in such cases,theair snpnlied for combustion is apart of'theairewhch islllg heated by the stove.

One object ci the inventionvis tozpijoviclean improved and novel aircontrol mechanism adapted to respond to changes inV ternperature'xothe air' suppy which it `controls.

Another Object' erA tnenyennon is to `prend@ air supply damper.'l'ifai'fingl a pilot da per associated therewith and rtl'iernlojs'tatie 'nieans connected to actuate the pilotfdaniper 'in a'dirfor closing itin response to rijsefof temperacr permitting it toppen inre`sponse"to"a drop in temperature, the fsame :'tlierrnostatic having a lost motion onneptionwith'the in damper which permitsjthe latter to'o'penin pense to a further drop intemperature." Itis supp-ly duct with a Ina-in damper andY pilot damper erein together with thermostatic controlmeans cr said dempers all designed for economicalfvcontruc-tion and ecient operation.' Other 'objects ad advantages of the invention vwill appear from following description taken in' connectionwi'th drawings ln which: Fig. 1 is a diagrammatic side elevationrepresenting a stove with an air supply duct-,embodyg this invention applied thereto." Fig. 2 is a top plan'viewoffthe air supply. duct itself shown on a larger scale.

3 is a vertical sectional View ltaken as indiat line 3-.3 on Fig.l 2 andshowing one Wall thereto, together with air Acontrol dempers in the duet and thermostatic -means 4 for actuating them, dempers beingshownin closed position.

Fig. e is a verticalsectionalview similar to Eig. D

dempers at fully openposlt'ion.

Fig. 5 is an end elevation taken-as, indicatedat line 5-5 on Fig. 3.

Fig. 6 is a transverse section looking v cliige'oizly rame and is takenas Vindicated .atlineJliL-Son se. 3. i

Fig. 7 is a detail perspectivetview lof the -pilot C-.an'iperalone.

o an object oi" the invention to provide an air oc tl e stove and the -air supplvduct ,connected 4 *Eigis a detail sectiona1 view taken as Acated at line18-'-'8o`n Fig. l2. While thereis shown and described herein certain specicstructure embodying the invention, it'willbe manifest to those skilled in the art that varioiismodiflcations and 1re-arrangements of the parts' may be'made without departing kfrom the spirit and =scope of the iinventionyand that the same is not limited to the particular form herein ,disclosed,V `exceptin sofar as indicated by the appended claims.

lThe stove 1 shown in Fig. 1 may be any con- Vehtionalsforrn of stove orheater in which air is employed to support' combustion, and the structnrewhich isthe subject ,ofthis invention is included within thevar supply duct 2 which is shown projetingwfrom one side of the stove i in FigjlLPreferably, and for convenience of conindistructiom'tljie duct 2 is of rectangular' cross- .45 but omitting the Wall Qf'iheisteve asd-.Showing 5D et the face of the Adampers andtheir supporting setion a-s seen inFig. 5, having side walls 3.3, a top wall 4 and a bottom wall 5. Obliquely secured 4within this vrectangular `tube 2 is a sheet metal frame 6'L having a ange 'lk hooked around the front edge'of the lower wallf:l of the air duct and having tonguesorlugs 8,18 which extend through Vslots 9, Sin the top' wall d and are bent down iiatly against said wall to hold the frame in position. Said "iframe may also have lateral stiffening fl'flEBS- IllvvhiQh iit snuglyagainst the -side walls '3 an'dwhich mayrbe'solderedor Welded thereto i fdesired,though this'is not of essential sigl{ Ihje',lateral portions of the frame provide lllgsllg- AH `4which arebent'at right angles to ythe iin linedplane of Vtheirame and which support a plvotrod'llZ. '.Amainjdamper plate I 3 is formed ',w'thjlngsvjtwhioh are journaled onjthe pivot "rod L2' and'` said damper plate inclndes aV lower seetionj .15 `which in closed position rests against ":thefonter: face'of jthe frame v6 as seen inFig.' `3, gvvhilfe:V the "npperjportion' i6 of the damper `fits snugly' against the rear vface of vthe Aframe 6 as also'seen in Fig'.j3. vThe loweredge 4of the section l'ncludes d iiange I1 whchserves tofstisffenthis por L on'lofthed'arnperjand alsogives it a definite vpreponderance of Weight over the 4upper portion iB sothat the main damper ls'initially biased by 'gravltyltofthe closed position in which it 'is shown The ppper section I6 of the main damper in- ,chides' anlapertre `-l'lwliich'is'seen in Fig. 6' as ia'wsiilostantially square vopening and a'pilotdamp'er ljjformed with U-shapedlugs 12o andjflts over 'p ions .0f the .Divot rod'AlZggthus formingapivpta vmountingwhicll is coaxial withthepivotal afiezsvs 3 mounting of the main damper I3. Guide lugs 2i, 2I project through the opening I8 adjacent its lateral margins to maintain the pilot damper I9 in proper relation to said opening. At the upper edge of the pilot damper portion which closes the opening I8 said pilot damper has a part 23 which extends angularly from the said portion and performs as a counterweight to bias the pilot damper by gravity to open position. Such open position is determined and limited by an arm 24 extending from the pilot damper below its pivot Y axis so as to swing against the rear or inner face of the main damper portion I when the pilot damper I9 swings away from the opening I8. The weight of the part 23 is Sufficient to overbalance the marginal preponderance of Weight mentioned above in section I5 of the main damper so that when the pilot damper swings open and the arm 24 engages the lower part I5 of the main damper both parts rotate about the pivot I2 until the portion 23 of the pilot damper strikes the down the material at the slits as indicated in Fig. 8. Also as a convenient feature of construction, it may be noted that the U-shaped lugs 2U', 23 engaging the pivot rod I2 require no special retaining means to hold them to the rod, since the chain 21 is constantly under tension exerted by the curved bimetallic thermostat arm 25 at all positions of its range of action and thus serves to hold the pilot damper on the rod I2.

I claim:

1. In combination with a stove or the like, an air supply duct therefor, a pivotally mounted main damper for said duct initially biased to closed position, said main damper having an aperture, a pilot damper pivoted coaxially with the main damper and dimensioned to close said ap- Y erture, biasing means urging the pilot damper bottom wall 5 of the air duct. Thus both dampers are normally biased by gravity to open position.

The thermostatic device shown in the drawings consists of a bimetallic bar or strip having one end secured flatly against the under surface of the top wall 4 as by a bolt 26 and having its free end curved downwardly therefrom and connected by a exible chain 21 to the pilot damper I9, as seen in Figs. 3 and 4. Figure 4 indicates approximately the form of the curved end portion of the thermostat 25 when cold and it may be understood that the two metallic components of the member 25 are so arranged that as its temperature increases its curvature tends to diminish, carrying the free end of the part 25 outwardly toward the outer end of the air duct 2 and away from the pivot axis of the dampers so that a pull is thus introduced through the chain 21 which first acts to swing the pilot damper I9 upward; this allows the main damper to tilt from its horizontal open position toward its inclined closed position, and nally the chain pulls the pilot damper into closed position against the inner face of the part I6, covering its aperture I8.

The curvature of the thermostatic member 25 Ymay be somewhat modified so as to alter the position of its free end for a particular temperature by providing an adjustable stop with which a portion of the member 25 will engage as it changes form from one limit to the other. Such a stop is shown in the drawings as an eccentric disc having a pivot shaft 3I journaled in the top wall 4 of the air duct 2 with a handle 32 secured to the shaft outside the duct and including a pointer 33 which may be arranged to traverse an arcuate scale 34 on the top wall 4 when the handle 32 is rotatively adjusted. It will be evident that such adjustment will determine the position of the free end of the arm 25 in accordance with the radius of the particular portion of the eccentric disc 30 which is presented for engagement with the intermediate portion of said arm 25 so that thether- Inostat may thus be caused to swing the dampers to full closed position at any chosen temperature within a limited range.

To insure that such adjustment of the eccentric disc 30 Awill not frictionally force the bimetallic element 25 laterally out of position and that said element shall be maintained positively in its proper relation to the other parts of the mechanism, the end portion of the element through which the securing bolt 26 extends is confined laterally by a pair of integral lugs 28 formed in the top wall 4 by slitting the wall and bending toward open position relative to said aperture, temperature responsive means connected to said pilot damper holding it closed at a predetermined temperature and operative to release it from closed position in response to a drop in temperature, and a lost motion connection through which the pilot damper then acts to bias the main damper toward open position in response to a further drop in temperature.

2. In combination with a horizontally extending air supply duct for a stove or the like, a main damper in the duct inclined at closed position therein and pivoted at a horizontal axis intermediate its upper and lower edges on which it swings into a substantially horizontal position when fully opened, said damper having an aperture positioned above its pivot axis, a pilot damper dimensioned to close said aperture and pivotally supported at an axis below the aperture, said pilot damper being gravitationally biased to open position and having an varm which extends below the pivot axis of the main damper and engages the lower portion of said main damper when the pilot damper falls open, thereby biasing said main damper toward its open horizontal position, and temperature responsive means mounted in the duct and subject to the temperature of air entering said duct, together with a flexible tie connecting the pilot damper to said means operative tohold said pilot damper closed at a predetermined temperature and to release it from closed position in response to a drop in temperature, said arm of the pilot damper engaging the main damper and swinging it toward open position in response to movement of the temperature responsive means occasioned by a further drop in temperature.

3. In combination with a room heating stove or the like, a draft intake housing having a stovecommunicating side and a room-communicating side, a pivoted primary valve for closing said housing normally biased to draft-closed position, a secondary valve pivoted coaxially with said primary valve and normally biased to draft-open position, means under the control of said secondary valve for engaging said primary valve to cause the latter to move to draft-open position, and temperature responsive means secured to the room side of said housing for operating said secondary valve and through it said primary valve for moving Iboth of said valves to draft-closed position.

4. A draft regulating apparatus for room heating devices or the like comprising, a rectangular housing member having a horizontal supporting pivot transversely thereof intermediate its extremities which communicate with said device and 5 with a. room atmosphere, a primary draft control valve carried by said supporting pivot and normally weighted to assume its draft-closed position and having therein a reduced-area aperture, a

secondary valve also supported on said pivot and 5 weighted to normally assume its draft-open position having a portion alined to cover said area aperture and a portion for engaging said primary valve to move the latter member to its draft-open position, a thermostatic control element secured 10 to said housing member on the room atmosphere side of said primary and secondary valves, and a exible member connecting said secondary valve with a thermostatic element for moving said secoondary valve and through it said primary valve 15 to draft-closing positions.

JOHN G. DUNVILLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

